1. Field of the Invention
This invention relates generally to the field of virtual computing, and more particularly, to a system and method for backing up a virtual machine that uses a storage device that bypasses the hypervisor I/O layer of the virtualization platform on which the virtual machine executes.
2. Description of the Related Art
A virtual machine (VM), also referred to as a virtual computer, is a software implementation of a machine (computer) that executes programs like a real machine. Virtualization provides the ability for multiple virtual machines to run together on the same physical computer. Each virtual machine may execute its own operating system and may appear to a user of the virtual machine to be the same as an independent physical computer. A user may interact with a virtual machine similarly as if the user were interacting with a physical computer. For example, various software applications may be installed on the virtual machine, and the virtual machine may enable the user to launch the software applications, provide input to the software applications, and view output from the software applications identically as if they were executing on a physical computer.
A virtual machine typically maintains its own set of files, similarly as a physical computer would, such as operating system files, application program files, data files, etc. Whereas the files of a physical computer are typically stored on a hard disk, files of a virtual machine are often stored in one or more virtual disk image files. A virtual disk image file represents the contents and structure of a hard disk drive, e.g., by representing disk sectors. Sectors of the virtual disk image file are allocated as necessary for storing the files used by the virtual machine. In addition to the sector data, the virtual disk image file also includes various data structures for managing the sector data, such as a sector bitmap indicating which sectors are currently in use and store valid data.